Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By reviewing the USDA zone info for Highland Park it's a good idea to estimate when you can plant periwinkles.

Planting Calendar for Periwinkles

Frost tolerance for periwinkles:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

You should not plant periwinkles until after the last frost because they require warm weather.

The earliest that you can plant periwinkles in Highland Park is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant periwinkles and expect a good harvest is probably August. You probably don't want to wait any later than that or else your periwinkles may not have a chance to grow to maturity. If you are starting your periwinkles indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost is on April 15 in Highland Park. It might get as low as -5°F during the coldest months of winter.

Always keep in mind that USDA zone info for Highland Park is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Highland Park you get a frost after April 15 so just be sure to be ready to protect your periwinkles in the event of a late frost.

USDA Zone Info for Highland Park

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Highland Park

You may be interested in your other planting guides for Highland Park.